The invention concerns a catalyst component for an alpha olephine-polymerizing catalyst, which comprises an organoaluminum compound, an electron donor, and a solid catalyst component which is obtained when a compound containing magnesium has reacted with a titanium halide compound. The present invention is also directed to a procedure for manufacturing this catalyst component, and to a procedure for polymerizing the alpha olefines, especially propylene, which makes use of the catalyst component.
Catalysts known in the prior art with high activity for polymerizing alpha olefines, which have been manufactured include an aluminum alkyl compound, an electron donor, and a halogenated titanium compound on a carrier substance comprising various magnesium compounds. Chlorinated magnesium compounds have generally been used as the magnesium compound, which may be, for instance, water-free magnesium chloride alone or together with other magnesium compounds, or an organic magnesium compound which has been prepared by halogenating organic magnesium compounds with the aid of chlorine-containing compounds.
In polymerizing catalysts of this type, the properties of the solid carrier component have significant influence upon the properties of the ultimate catalyst, e.g. upon its activity. These properties can be substantially influenced through the mode of manufacturing of the carrier component.
The present invention concerns a catalyst component in which the carrier component has been prepared from water-soluble compounds containing magnesium which may be natural minerals or synthetic minerals. Magnesium minerals have been used as starting material in preparing inert carrier components for Ziegler-Natta catalysts for the purpose of polymerizing olefines. However, it has turned out to be difficult to manufacture active Ziegler-Natta catalysts from various magnesium compounds and from minerals containing the same, in particular those catalysts for the polymerizing processes of propylene, because in these processes the catalysts are highly sensitive to moisture and to the crystallized water contained in the carrier. Even minimal quantities of crystallized water already significantly reduce the activity of the catalyst.